﻿$(document).ready(function () {
    var textbox = $('#txtHelloWorld');

    $('#btnOk').click(function () {
        var textBox = $('#txtHelloWorld');

        if (textBox.val() == '') {
            textBox.css('background', 'red');
            return false;
        }
    });

    $('#txtHelloWorld').keypress(function () {
        $(this).css('background', 'white');
    });
});